Pentax
K-3 Mark III
APS-C DSLR flagship with optical viewfinder and weather sealing.
$1,999
Launch priceReleased Apr 2021
Sigma
fp L
World's smallest full-frame interchangeable camera with 61MP and L-mount.
$2,499
Launch priceReleased Jul 2021
fp L is 2 months newer.
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Wins
K-3 Mark III
Wins
fp L
5 categories tied
Which would you choose?
TL;DR — Key differences
- AK-3 Mark III has higher RAW buffer depth (120 frames vs 12 frames)
- AK-3 Mark III has higher Battery life (CIPA) (640 shots vs 240 shots)
- Bfp L has higher Resolution (61 MP vs 25.7 MP)
- AK-3 Mark III has higher AF points / zones (101 vs 49)
- AK-3 Mark III has higher 4K max frame rate (60 fps vs 29.97 fps)
Key specs at a glance
Size and weight, to scale
📸 Snap this size diff to shareK-3 Mark III
138 × 98 × 88 mm
520 g (1.15 lb / 18.34 oz)
Credit card
85.6 × 54 mm
for scale
fp L
113 × 70 × 45 mm
427 g (0.94 lb / 15.06 oz)
K-3 Mark III is 25mm wider, 28mm taller, and 43mm thicker than fp L.
K-3 Mark III is 93 g heavier than fp L.
Depth (front-to-back): 88mm K-3 Mark III · 45mm fp L
Back view, to scale
Width × Height — same proportions as the front of the body.
K-3 Mark III
138 × 98 mm
Credit card
85.6 × 54 mm
fp L
113 × 70 mm
Top view, to scale
Width × Depth (front-to-back) — see which body is chunkier on the table.
K-3 Mark III
138 × 88 mm
Credit card
85.6 × 54 mm
fp L
113 × 45 mm
Sensor size, to scale
K-3 Mark III
23.5 × 15.6 mm · APS-C
367 mm² area
fp L
36 × 24 mm · Full Frame
864 mm² area
2.4× larger sensor area = shallower depth of field and better low-light performance.
Lens ecosystem
Native lens selection
K-3 Mark III
✓ more lensesPentax K
70+
native lenses available
fp L: mount data unavailable
Counts include current first-party and major third-party native autofocus lenses.
Use-case scoring
Which one for what?
Algorithmic scores from verified specs · 10 = best in class
Why pick one over the other
Reasons to choose
K-3 Mark III
Dimensions (W×H×D mm)
Adds 138, 98, 88
Card types
Adds SD UHS-II
RAW buffer depth
120 frames vs 12 frames — higher is better
Battery life (CIPA)
640 shots vs 240 shots — higher is better
AF points / zones
101 vs 49 — higher is better
4K max frame rate
60 fps vs 29.97 fps — higher is better
Burst (electronic)
20 fps vs 10 fps — higher is better
Codecs
Adds H.265
Reasons to choose
fp L
AF low-light limit
-5 EV vs -3 EV — lower is better
Dimensions (W×H×D mm)
Adds 112.6, 69.9, 45.3
Card types
Adds SD, SDHC, SDXC
Codecs
Adds CinemaDNG, MOV
Resolution
61 MP vs 25.7 MP — higher is better
AA filter
Only fp L supports it
Internal RAW video
Only fp L supports it
Weight
427 g vs 520 g — lower is better
Both cameras share
- ✓ISO min (native) — Both 100
- ✓ISO max (native) — Both 25,600
- ✓Eye AF — Both support eye af
- ✓Animal / bird AF — Both support animal / bird af
- ✓Pre-Capture / Pre-Release — Both support pre-capture / pre-release
- ✓Max video bit rate — Both 150 Mbps
Pros & cons at a glance
Editorially curated highlights and trade-offs.
K-3 Mark III
Pros
- ✓Optical viewfinder
- ✓Weather sealed
- ✓IBIS in DSLR
Cons
- –DSLR system declining
- –APS-C
- –Limited video
fp L
Pros
- ✓Tiny full-frame
- ✓61MP
- ✓L-mount
- ✓Unique industrial design
Cons
- –No IBIS
- –Small battery
- –Minimal ergonomics
Decided which one is right for you?
Compare live prices for the K-3 Mark III and fp L at major authorized retailers.
Pentax K-3 Mark III
Sigma fp L
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Full specifications
✓ = category winner
Frequently asked
Quick answers generated from verified specs.
Which is better for travel, K-3 Mark III or fp L?
K-3 Mark III scores 8.5/10 versus 5.0/10 for fp L — 520g — compact and travel-friendly.
What's the resolution difference between the K-3 Mark III and fp L?
K-3 Mark III is 25.7 MP and fp L is 61 MP, so the fp L captures more detail for cropping and large prints.
Do the K-3 Mark III and fp L have in-body image stabilization?
K-3 Mark III has 7-stop in-body image stabilization, while fp L does not have IBIS.
Which shoots faster bursts — the K-3 Mark III or the fp L?
K-3 Mark III reaches 20 fps electronic. fp L reaches 10 fps electronic.
What's the weight difference between the K-3 Mark III and fp L?
K-3 Mark III weighs 520 g and fp L weighs 427 g, so the fp L is 93 g lighter.
Do the K-3 Mark III and fp L record 4K video?
K-3 Mark III: 4K up to 60p. fp L: 4K up to 29.97p.
Are the K-3 Mark III and fp L weather sealed?
K-3 Mark III: Yes. fp L: Yes.
Which has better battery life?
Rated battery life is 640 shots (CIPA) for the K-3 Mark III and 240 shots for the fp L, giving the K-3 Mark III the edge.
How much does each cost?
K-3 Mark III launched at $1,999 and fp L at $2,499. The K-3 Mark III is $500 less.
Can't decide between two? Compare a third camera.
Add any camera to get a three-way K-3 Mark III vs fp L vs X comparison.
Specs sourced from manufacturer data. Use-case scores algorithmically derived. Last reviewed July 2026.
Product images courtesy of Pentax and Sigma press materials.